1. Field of the Invention
Embodiments of the present invention generally relate to marine seismic surveying, and more preferably, to methods for acquiring seismic data.
2. Description of the Related Art
Seismic exploration is widely used to locate and/or survey subterranean geological formations for hydrocarbon deposits. Since many commercially valuable hydrocarbon deposits are located beneath bodies of water, various types of marine seismic surveys have been developed. In a typical marine seismic survey, seismic streamers are towed behind a survey vessel. The seismic streamers may be several thousand meters long and contain a large number of sensors, such as hydrophones, geophones, and associated electronic equipment, which are distributed along the length of the each seismic streamer cable. The survey vessel also includes one or more seismic sources, such as air guns and the like.
As the seismic streamers are towed behind the survey vessel, acoustic signals, commonly referred to as “shots,” produced by the one or more seismic sources are directed down through the water into strata beneath the water bottom, where they are reflected from the various subterranean geological formations. Reflected signals are received by the sensors, digitized, and then transmitted to the survey vessel. The digitized signals are referred to as “traces” and are recorded and at least partially processed by a signal processing unit deployed on the survey vessel. The ultimate aim of this process is to build up a representation of the subterranean geological formations beneath the streamers. Analysis of the representation may indicate probable locations of hydrocarbon deposits in the subterranean geological formations.
Many of the subterranean geological formations are better represented with low frequency seismic signals. Accordingly, a need exists in the art for one or more methods for acquiring seismic signals from subterranean geological formations that are better represented with low frequency seismic signals.